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Ledov VA, Golovina ME, Markina AA, Knirel YA, L'vov VL, Kovalchuk AL, Aparin PG. Highly homogenous tri-acylated S-LPS acts as a novel clinically applicable vaccine against Shigella flexneri 2a infection. Vaccine 2019; 37:1062-1072. [PMID: 30670300 DOI: 10.1016/j.vaccine.2018.12.067] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Revised: 12/08/2018] [Accepted: 12/30/2018] [Indexed: 12/24/2022]
Abstract
Shigellosis, a major cause of diarrhea worldwide, exhibits high morbidity and mortality in children. Specificity of Shigella immunity is determined by the structure of the main protective O-antigen polysaccharide component incorporated into the lipopolysaccharide (LPS) molecule. Endotoxicity, however, precludes LPS clinical use. Thus, there is still no vaccine against the most prevalent shigellosis species (serotype S. flexneri 2a), despite ongoing efforts focused on inducing serotype-specific immunity. As LPS is highly heterogenous, we hypothesized that more homogenous pools of LPS might be less toxic. We developed a method to generate a homogenous S. flexneri 2a LPS subfraction, Ac3-S-LPS, containing long chain O-specific polysaccharide (S-LPS) and mainly tri-acylated lipid A, with no penta- and hexa-acylated, and rare tetra-acylated lipid A. Ac3-S-LPS had dramatically reduced pyrogenicity and protected guinea pigs from shigellosis. In volunteers, 50 µg of injected Ac3-S-LPS vaccine was safe, with low pyrogenicity, no severe and few minor adverse events, and did not induce pro-inflammatory cytokines. In spite of the profound lipid A modification, the vaccine induced a prevalence of IgG and IgA antibodies. Thus, we have developed the first safe immunogenic LPS-based vaccine candidate for human administration. Homogenous underacetylated LPSs may also be useful for treating other LPS-driven human diseases. Clinical trial registry: http://grls.rosminzdrav.ru/.
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Affiliation(s)
- Vladimir A Ledov
- Laboratory of Carbohydrate Vaccines, National Research Center-Institute of Immunology, Federal Medical Biological Agency of Russia, 24, Kashirskoe Shosse, Moscow 115478, Russia
| | - Marina E Golovina
- Laboratory of Carbohydrate Vaccines, National Research Center-Institute of Immunology, Federal Medical Biological Agency of Russia, 24, Kashirskoe Shosse, Moscow 115478, Russia
| | - Anna A Markina
- Laboratory of Carbohydrate Vaccines, National Research Center-Institute of Immunology, Federal Medical Biological Agency of Russia, 24, Kashirskoe Shosse, Moscow 115478, Russia
| | - Yuriy A Knirel
- N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 47, Leninsky Prospect, Moscow 117913, Russia
| | - Vyacheslav L L'vov
- Laboratory of Preparative Biochemistry, National Research Center-Institute of Immunology, Federal Medical Biological Agency of Russia, 24, Kashirskoe Shosse, Moscow 115478, Russia
| | - Alexander L Kovalchuk
- The Virology and Cellular Immunology Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, NIH, Rockville, MD 20852, United States
| | - Petr G Aparin
- Laboratory of Carbohydrate Vaccines, National Research Center-Institute of Immunology, Federal Medical Biological Agency of Russia, 24, Kashirskoe Shosse, Moscow 115478, Russia.
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Kintz E, Goldberg JB. Regulation of lipopolysaccharide O antigen expression in Pseudomonas aeruginosa. Future Microbiol 2008; 3:191-203. [DOI: 10.2217/17460913.3.2.191] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Pseudomonas aeruginosa is a Gram-negative bacterium that is ubiquitously found in the environment. It is an important opportunistic pathogen in immunocompromised patients and causes life-threatening lung infections in individuals with cystic fibrosis. A prominent virulence factor for many Gram-negative bacteria, including P. aeruginosa, is lipopolysaccharide (LPS), which is an immunodominant antigen located in the outer portion of the outer membrane. P. aeruginosa produces two O antigens that are attached to lipid A + core: a B-band O antigen and an A-band O polysaccharide. The B-band O antigen-repeating unit of LPS is responsible for serotype specificity; strains lacking O antigen have been shown to be less virulent in animal models of infection. What is less well understood is how the O antigen chain length is regulated and why P. aeruginosa and some other bacteria show two preferred O antigen lengths. P. aeruginosa encodes two genes encoding O antigen chain length regulators. These genes, wzz1 and wzz2, influence the expression of the long and very long chain lengths, respectively. The long chain length appears more important for resistance to the action of sera and virulence in a mouse model of infection, while the very long chain length appears to be more sensitive to environmental stress conditions. Studies in other bacteria point to regulation at the level of transcription and complex formation as being involved in determining the O antigen chain length and may provide clues to the regulation in P. aeruginosa.
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Affiliation(s)
- Erica Kintz
- Department of Microbiology, University of Virginia Health System, 1300 Jefferson Park Avenue, 7230 Jordan Hall, Charlottesville, VA 22908-0734, USA
| | - Joanna B Goldberg
- Department of Microbiology, University of Virginia Health System, 1300 Jefferson Park Avenue, 7230 Jordan Hall, Charlottesville, VA 22908-0734, USA
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Carter JA, Blondel CJ, Zaldívar M, Álvarez SA, Marolda CL, Valvano MA, Contreras I. O-antigen modal chain length in Shigella flexneri 2a is growth-regulated through RfaH-mediated transcriptional control of the wzy gene. MICROBIOLOGY-SGM 2007; 153:3499-3507. [PMID: 17906147 DOI: 10.1099/mic.0.2007/010066-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Shigella flexneri 2a 2457T produces lipopolysaccharide (LPS) with two O-antigen (OAg) chain lengths: a short (S-OAg) controlled by WzzB and a very long (VL-OAg) determined by Wzz(pHS-2). This study demonstrates that the synthesis and length distribution of the S. flexneri OAg are under growth-phase-dependent regulation. Quantitative electrophoretic analysis showed that the VL-OAg increased during growth while the S-OAg distribution remained constant. Increased production of VL-OAg correlated with the growth-phase-regulated expression of the transcription elongation factor RfaH, and was severely impaired in a DeltarfaH mutant, which synthesized only low-molecular-mass OAg molecules and a small amount of S-OAg. Real-time RT-PCR revealed a drastic reduction of wzy polymerase gene expression in the DeltarfaH mutant. Complementation of this mutant with the wzy gene cloned into a high-copy-number plasmid restored the bimodal OAg distribution, suggesting that cellular levels of Wzy influence not only OAg polymerization but also chain-length distribution. Accordingly, overexpression of wzy in the wild-type strain resulted in production of a large amount of high-molecular-mass OAg molecules. An increased dosage of either wzzB or wzz(pHS-2) also altered OAg chain-length distribution. Transcription of wzzB and wzz(pHS-2) genes was regulated during bacterial growth but in an RfaH-independent manner. Overall, these findings indicate that expression of the wzy, wzzB and wzz(pHS-2) genes is finely regulated to determine an appropriate balance between the proteins responsible for polymerization and chain-length distribution of S. flexneri OAg.
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Affiliation(s)
- Javier A Carter
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, PO Box 174 Correo 22, Santiago, Chile
| | - Carlos J Blondel
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, PO Box 174 Correo 22, Santiago, Chile
| | - Mercedes Zaldívar
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, PO Box 174 Correo 22, Santiago, Chile
| | - Sergio A Álvarez
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, PO Box 174 Correo 22, Santiago, Chile
| | - Cristina L Marolda
- Infectious Diseases Research Group, Siebens-Drake Research Institute, Department of Microbiology and Immunology, The University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Miguel A Valvano
- Infectious Diseases Research Group, Siebens-Drake Research Institute, Department of Microbiology and Immunology, The University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Inés Contreras
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, PO Box 174 Correo 22, Santiago, Chile
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